Process of refining salt and recovering its impurities as by-products.



l C. GLASER & G. J. MULLER. PRDESS DF REFINING- SALT AND REGQVERING ITS IMPURITIES AS BY-PRDDUUTS. v

APPLIUATIM FILED nu 17, 1909.

Patented May 10, 1910y .MSSS

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'UNITED sfrATEs Param* OFFICE.

CHARLES GLASEB AND GEORGE J. MULLER, 0F BALTIMORE, MARYLAND,

PROCESS 0F REFINING SALT AND EECOVERING ITS IMPUBITIES AS BY-PBODUCTS.

Speuication of Letters Patent.

Patented May 10, 1910.

Application tiled Hay 17, 1999. Serial ljfo. 498,525.

To all whom 'it may concern:

Be it known that We, CHARLES Grinsen and GEORGE J. MULLER, citizens of the United States, residing in the city of Baltimore, State of Maryland, have invented a new and useful Process of Relining .Salt and Recovering Its Impar-ities as By Products, of which the following is a specification.

The invention relates to the separation from salt (sodium chlorid) of the impurities which occur with it in nature and nrticularly those impurities with which 1t is generally sold in crude sta-te prior ,to refining.

The object of the invention is to remove the impurities from .the salt either absolutely as when the salt is desired for chemical or other uses Where even a fractional percentage of impurity is undesirable or to reduce the proportion of impurities to such an extent as will .make them wholly unobjectionable for ordinary commercial pur oses; and to attain those results in a sin-ipe and etlicient manner, and at a moderate cost.

One feature of the present invention oonsists in removing .impurities from salt bythe use of reagents of such character that the mass of salt or the elementsthercof are increased on addition of each reagent and that only those elements of the impurities are thrown down or removed which do not enter into the composition of salt or which will not combine with an element of salt to produce an ingredient which may be .thereafter attacked by other reagents; in other words this feat-ure of the invention consists in treating the impurities with reagents which while precipitating elements that do not enter into the composition of salt, will add to the solution one of the elements of salt in such form or so combined that its associated element or elements may thereafter be precipitated by another reagent or rea nts that will supply the other element of sa t, so that the process is, in its effect, accumnlative as to the sodium chlorid to be produced.

Another feature of the invention consists in purifying salt by leaching itwith a solvent which consists of a satura-ted solution of pure salt containing acid of such character and restricted tlunntity as to dissolve certain impurities inso uble in water and thus making them amenable to further treatment and removal, the dplu-e salt solution being prefer.- ably obtaine by the process constituting the lirst feature of the invention and this portion of the rocess being refernbly re eated after each caching or a er such num er of leachings as may develop a workable percenta e of impurities in the leaching liquor, in orgel' to use the solvent repeatedly.

Another feature of the invention consists in treating a. saturated solution of impure salt with hydrochloric acid in quantit so restricted as to avoid precipitating so ium chlorid, yet suliiciently large to malte itan eiecti've solvent lfor certain impurities and thereby render such impurities amenable to the reagents to be used.

Another feature of the invention consists in introducing into the'solution of the salt with its impurities, 'a single reagent, such for instance as barium chlorid,"having'the capacity for reducing a plurality of impurities having a. common characteristic (sulfates) and while precipitating the sulfur content of all in a single substance (BaSQJ converting the bases of such impuritiesV (e. g. NaZSCL, CaSO MgSOQ into chl'orids.

Another feature consists in adding to the solution of salt and'its impurities, prefer'- ably after the impurities have been reduced to chloride, a special reagent foreach of several impurities, in such quantity 4that each reagent acts upon the impurity intended to be removed thereby. And inasmuch ast-he impurities of salt either constitute or co11 tain elements of commercially valuable chemical products, it is desirable to so conduct the process as to save, in commercial form, those impurities that have a commercial value; still another feature of the invention, consists in applying the said reagents successively to the solution and separating the precipitates and doing ,this in such a way, as to react upon the impurities successively in the order in which it is desired to precipitate and recover them and with reagents not only suitable in character to precipitate the elements to be removed, but suitable in quantity to limit each reaction to the specific impurity to be attacked by cach reagent, at the particular step in the process.

Another feature of the invention consists in employing alkaline cnl'bonntes (.for example, i ound dolomite) as a reagent for eliminating iron and neutralizing the acid menstruum, without removing salt producing elements.

Further features consist in certain details in the carryin will be lier out of the process which tcr fully described aud par out in thc claims.

cina.

To aid in comprehcndiug the nature ot' thc invention,

we have illustrated by a graphic chart forming a part of this speciticatlom various steps in several s ecific processes embodying which steps ends to' be attained and the conditions under which the the features o naturally vary the invention, according to the o eration is to be carried out.

The several arger circles of the chart may bc taken to illustrate in which the reactions chemical symbols therein indicate their con tents, while the a series of receptacles take place and the contained smaller circles are to be understood as representin" reagents introduced and the exterior smaller circles as representing precipitates developing from the reaction in the preceding receptacles.

It will be understood that in the several steps of the process, the reactions will be favored by constantly agitating the contents of the receptacles and maintaining a temperat-ure of from 50 to 60D C.

Referring first to a process where it is desired to save such of the impurities as have suiiicient commercial dling them separately,

carried on chemical symbols 4, 5, 6 and '7 or 7b, duce sodium chlorid; or may step farther treating W left hand duce substantially chemically chlorid as indicated in receptacle 8; or

value to justify lianthe process may be as indicated graphically by the in the receptacles 1, 2, 3, or l to 5, 6 and 7 to probe carried a from receptacles 7, or 7", by ith the reagents indicated at the sides in said receptacles to propure sodium from either of the receptacles T, 7*- or 7b a step may be taken as indicated by the reagent at the right hand side in each receptacle to produce 100 indicated in the receptacle 8a. in rece tacle 1,

ent so ium sociated impurities, sulfate, calcium sulfate, calcium chlorid, perhaps other metallic ydrochloric acid is added in certain restricted quantity to throw chemically pure sodium chlorid as Thus we find besides the principal ingredichlorid 0r commercie salt, its asferric liydi-oxid, sodium magnesium sulfate, magnesium chlorid with hydroxids. To this it slightly beyond the neutral point, which has the effect of dissolving as chloride, Ferro-cyanid of other metallic oxids tacle 2. ed with the iron and as indicated iii rece sodium is now ad the result that ferri-ferro cyanid, of commarcial value is precipitated, while the chlorin element of the :ferrie chlorid, of recap tacle 2, combines with the sodium element ot that all of the reagent to form salt, which is added to the original content. next eliminated by adding ceptacle S-barium chlori he sulfuric radica-l is the reagent of redM-witli the result the sulfur contents combined with lciuin and magnesium are taken u by the barium und precipitated as llaS0,. l.: cre again, the sodium clement combines with chlorin element of the reagent added and. forms more salt. und the calcium and magnesium exist as calcium and uuignesuui chlorid; sodium carbonate is now added to receptacle 4 in just suilicient quantity to pref cipitate any remaining chloride of heavier metals and a small per cent. of calcium present which may be discarded. Here again the clilorin element combines with the sodium element added and produces more salt and this is continued in receptacle until we find in receptacle 6 that all the chlorin ot' the calcium impurity has united with the sodium of the reagent to forni more salt while the calcium is precipitated in the form of carbonate, and magnesium alone remains. Instead of introducing sodium carbonate in receptacle 5, sodium hydroxd can he introduced therein to develop the conditions indicated in receptacle 6 Where the magnesium has been precip`tated iiithe forni ot' hydroxid, the clilorin element of the impurity combining with the sodium of the reagent. to forni more salt and the calcium impurity alone remains; the latter being?r thereafter removed by introducingr the sodium carbonate to produce the condition illustrated in receptacle 7 where salt alone remains. Again referring to receptacle 6 the remaining magnesium impurity nia be worked out by sodium hydroxid to produce the conditions indicated in the receptacle 7b, or by the addition of sodium carbonate precipitate the magnesium as a carbonate as in 7. If the process is started as from 2, 2 or 2d then the product in receptacle 7, 7 or T will be a saturated solution of substantially pure sodium chlorid which is much purer than any product of the kind that can be bought iii the market today and the residual impurities will be unweghable traces which are not objectionable in salt for table purposes.

lWhen the purification is started as in 1 and 3" and brought to the condition illustrated in either of the receptacles T, or the salt is brought to a pure state by further treatment in either of two ways; that is to say the solution may be neutralized with a suiicient quantity of hydrochloric acid and evaporated, when it will produce substantial y chemically pure sodium chlorid with an univeigliable trace of impurities due to contamination or contact with uuichincry etc. as indicated in receptacle S, or the con tents ot either receptacle 7, T, T" may be treated with au excess of hydrochloric acid to precipitate au absolutely chemically puri` sodium chlorid as indicated in iecel'itaclc t't. It is not indispensable that steps from 1 to 7, 7 or 7 or 8 or 8a be carried on .successively as indicated; on the contrary satisfac tory results may be obtained by commencing as indicated in receptacle 2, with substan tin-ily the same impurities as indicated for the reixptacle 1 and there introducing first the barium chlorid und then sodium ciu'bouutc as reagents und climinatin r ot. once all impurities excepting chloride o calcium and magnesium as indicated in rece )taule 4, the precipitates being a mixture w ich may be discarded. Then the fifth ste may be perv formed and the process carrie( from thereon in either of the ways already explained. Or the process may be carried from the second to the seventh Step directly, as for mst-'ance'by taking the salt solution with the original impuritles as indicated in receptacle 2.c and there introducing three reagents, first barlum chlorid, and subsequently sodium carbonate and sodium hydroxid and precipitating the iron-sulfatecalciumand ma gnesium-impurities together with all the elements except those that enter into the composition of salt and at the same time combine all salt roducinv elements of the original impurities as well as of the reagents introduced to form salt, thereby arriving at the stage indicated in each of the receptacles 7, i" and 7", from which point. the process may be carried to completion by developin the conditions of the receptacle 8 or of tie receptacle 8a as may be desired. 0r the process may be carried on as from 9. down to ste 5 when the salt. will contain but traces o any sulfate impurities which are notobjectionable and are -not desired to be removed. Here sodium carbonate is added in quantity just suiiicient to precipitate a small per cent. of calcium as calcium carbonate yet enough to carry with it all iron, aluminum and other metallic hyv droxds. Here the sodium element combines with the chlorin element of the impurity and forms more salt and the brine is then treated as from the fifth step down. In commercial use it will be desirable to employ a cheap source of alkali for the neutralization of acidulated brine and the removal of iron and other allied metals. This may be carried out in the series vof steps commencing with 3b which contains an acidulated brine partly neutralized by dissolving and carrying with itthc impur-dies which it takes up 1n the leaching process. Barium chlorid is nou' added to precipitate the sulfate content as BaSO.. The solution is now completely neutralized by addin a carbonate of one or sew eral alkaline eart s such as dolomite, to remove iron and other allied mota-ls and to.

leave only the chloride of calcium and magnesium in solution with sodium chlorid as already described with reference to reccp tacle 5 to be treated by the steps forth.

Havin outlined the chemistry of the process, we will next proceed to describe an illustrative commercial process in which our invent-ion is applied under actual conditions when the impurities are to he recovered iu full and separately and prepared for commerce. Brine from o well muy he used or .sodium chlorid muy he dissolved to make a saturated solution, littered or otherwise separated from dust und flirt, thel ln'iue is now heated and kept at 5U to 60 l., hydrochloric acid is added 1u restricted quantity just sollicient to dissolve any colloidal or suspended hydroxide of heavier metals as chloridev without precipitating any sodium chlorid, terrocyanid of sodium is now added to precipitate the iron of the ferrie chlorid as ferri-ferro cyanid, the brine now filtered or otherwise separated barium chlorid is now added to precipitate all sulfates as barium sulfate and the brine is again filtered or otherwise separated, next a small quantity of solution of a. sodium carbonate is added to the brine for the purpose of precipitating in the form of basic carbonatos any remaining heavier metals from their chloride. llith this will be precipitated a little carbonate of alkaline earth. The brine is again filtered or otherwise separated. The precipitate will ordinal-ily be discarded. The brine, still hot is now cautiously treated with a moderately strong solution of sodium carbonate in just such restricted quantity as to throw down, as carbonate, any alkaline earth such as calcium, but not magnesium. The brine is now filtered orotherwise separated from the precipitated carbonate which is washed clean, dried and is ready for sale. The brine, which contains now only magnesium as a foreign base to be removed, is now treated with sui!- ficiently strong clean sodium carbonate solution to precipitate all of the magnesium present as magnesium carbonate which is separated from the brine in a well known way` washed clean. and dried, when it: is ready for sale, or the brine is treated with n moderately strong sodium hydroxid solution to precipitate the magnesium as magnesium hydroxid, which is separated from the brine, washed clean dried and finally eelt-ined. when it is ready for sale. Both are of a high degrec ot' purity. answering to the requirements of U. S. Phew/rampmia. The brine thus obtained yields upon evaporation a salt oi. a high purity which will stay dry in any climate.

in meeting conditions of trade. a brine, made as described above may be successfully used to purify a solid .salt of commerce and reduce it. to the same fine condition. For example :-A ,small quantity of h x-'flrcjx-,hlm'ic acid (l to 4% prefcralily) is added to the purified briml and with this solution` salt is leached in suitable vessels. After dissolving the impurities contained therein. the salt. is washed with successive portions of the uuacidulatcd brine. until alll impurtii-s which have been dissolved are removed. The brine thus used as a leaching ugent mar lw, neutralized. purified and regeln-ratei as often as necessary for repeated or separate use. As another example, when only the calculn and magnesium are to be recovered, sodium chlorid may be dissolved to produce a saturated brine or a brine of a specific gravity of 1.2 or over, such as forms the usual product of concentration of salme well-water and ready to be reduced to solid salt by further evaporation in the usual manner will be submitted. In a suitable tank provided with steam heat, a convenient quantity of brine is placed and heated to about {S0-60 C. Since the composition of the brine is easily ascertainable by analysis, the approximate quantities of preclpltatmg reagents are Abest calculated by such method. Barium chlorid is now added to prooi itate all. sulfatos as 1321504 after which u so ution containing about 10% of sodium carbonate is added in quantity slightly in excess of what is actually required for the precipitation of iron, aluminum and allied oxids. The oxicls, mixed with a small quantity of calcium carbonate are allowedto settle and the clear supernatant salt. brine is drawn olf into a second tank, similarly provided with steam heat. The temperature of the brine is still kept at about 5060 C. and under agita-v tion of the brine more of the 10% sodium carbonate solution is introduced, (ap roximately the amount calculated from anaysis) but toward the end careful observation is made to determine whether or not any mag nesium carbonate appears. YVhen this point is reached, a sample of tbe brine is tested for calcium. If a positive reaction is obtained, cautiously more of sodium carbonate is add ed under agitation of the brine, until magnesia is again observed to separate, when the above mentioned chemical test is repeated, and so on until all the calcium is removed. A careful operator will soon learn to seethe end point, so that seldom more than one chemical test will be necessary. After allow ing the calcium carbonate to settle the clear liquid is transferred to a third tank, in which magnesium hydroxid or magnesium carbonate is precipitated with the required quantity of sodium hydroxid or sodium carbonate solution, which may be of a strength of 30% or over, to avoid undue dilution of the brine. After settling of the magnesium hydroxid or magnesium carbonate, the brine is drawn off clear, and after neutralization with pure hydrochloric acid. is now ready for boiling down to pure solid salt or for use as a leaching;r solution for purification of ordinary solid salt-. as alreadyT intimated above and au example of which is given hereinafter.

The diil'ercnt precipitates contained in the three settling tanks above referred to are separately drawn from their respective tanks and freed from the remaining;` brine by filtration or otherwise. The brine so obtained is added to the next charge of brine in the sume stale of purification. The sediment from the firsttnnk, consisting principally of barium sul fates and basic carlmuates of iron and alun'iinuui und sonic calcium carbonate may be discarded. The sediment from the second tank is washed carefully in the filter until free from sodium clilorid, and then dried with or wit-hout heat. This producesa calcium carbonate ofa hiefh degree of purity. The sediment from the third tank is washed carefully in the filter until free from sodium clilorid, then dried as is usual in the production of magnesium carbonate or finally ca1- cined, as is usual in tbe production of mag nesiiun oxid. It will fully answer the requirements of the U. S. Phmmacopz'a. The quantities of by-products thus obtained de pend upon the quantities of basic impurities contained in the brine, and as these vary in thc product of every well, no close figures can be given. The quantities of calcium carbonate obtainable vary from one to three per cent., of magnesium from one quarter to one per cent. In boiling down a purified brine for solid salt in vacuum pans an incrust-ation of the apparatus by sulfatos and basic chloride of calcium and magnesium is entirely obviated, thus removing one of the most serious and costly troubles of the salt maker. During boiling care is taken that no fresh impurities are introduced.

The purifying of commercial table salt by leaching with purified brine is not specificallyr claimed herein but. is made the subject matter of our divisional application, filed November 17, 1909, Serial No. 525,566. It may be accomplished as follows. 1000 kilograms of commercial table salt are placed in a suitable leaching tank, provided with a filtering bottom. To 1000 kgs. of puried brine 10 to l0 kgs. of muriatic acid are added in a suitable storage tank placed above. the leaching tank. After thorough mixing, this acidulated brine is allowed to run into the leaching tank completely covering the salt therein. It is allowed to stand in contactwith the salt for 2 to 6 hours and is then dran-*n ott and pumped back into the storage tank. 1000 kgs. of pure brine solo tion is nonv added in portions of Q50 kgs. at a time, to the salt in the leaching` tank. the earlier portions carrying with them the. remainingr impurities and acid` `While the last port-ion will pass through as pure brine. The salt now removed from the leur-hina tank and dried in a well-known manner. The yield is nearly 1000 kgs. The leaching brines are kept separate so as to allow their separate use. the last portiononly, bein;r rcplaced by fresh puro brine. taking.' the place of the previous lot, etc. When the acidulated brine has been used so often as to show an accumulation of workable impurities. it is removed and replaced by fresh acidnlated brine, made from the advanced washing brines ln' addition of l0 to l0 kgs. of muriatic arid to the i000 kgs. ot' brine. ln prov tire the old acid liriuc is treated with barium chlor'id to precipitatil all sult'urio acid :unl neutralized preferably either hy an alkahml solution or by tiuely ground earthy rai'- lionales .such as dolomite, which permits only the calcium and magnesium impuritiesl Ito remain, the brine is non' separated from u` precipitates and is tli'cn treed 'from all bases except sodium chlorld in a manner above described for purit`},'inp, brine.

Having thus described our invention, what we claim as new therein and desire to secure by Letters Patent, is:-

1. The process of purifying rid which consists in adding to a solution of the impuresodinm chlorid a quantity of liyt'lrochloric acid sufficient to dissolve contained im urity not wholljir soluble in water but insu icient. to precipitate any of the sodium chlorid, then adding to the solution a reagent suitable in character and quantity to rea-ct upon and render the impurity separable from the sodium chlorid and at the Same time add to the solution an element of sodium chlorid.

2. The process of purifying sodium chlorid which consists in adding to a solution of the impure sodium chlorid a quant-ity of hydrochloric acid sutiicientto dissolve con tained impurity not wholly soluble. in water butl insuiicient to precipitate any of the sodium chlorid, then adding to the solution a reagent suitable in character and quantity to react upon and render the impurity se A arable from the sodium ehlorid and att e same time increase the mass of salt.

3. The process of removing from sodium chlorid an impurity not whoily soluble in water, which consists in dissolving the impurity by adding to the solution a quantity of hydrochloric acid sufficient therefor but insufficient to precipitate any of the sodium chlorid, then adding to the solution a reagent suitable in characte and quantity to react upon and render the impurity separable from the sodium chlorid and which reagent is also capable of adding to the solution an element of said chlori 4. The process of removing from sodium chlorid, a plurality of impurities not wholly soluble in water, `which consists in adding to the im ure solution` a quantity of hyd rochloric acid sufficient to dissolve the impurities but` insuicient to precipitate anir of the sodium chlorid, and then subjecting the im purities to a reagent. which renders them separable from the sodium clilorid and furnishes an element of sodium chlorid to the solution.

5. The process of removing from sodium chlorid a plurality of impurities not. wholly soluble in water, which consists in adding to an impure solution of the sodium chlorid, a.

sodium chlol i l l iuantity of hydrochloric arid, sulliciuut to dissolve the said impurities hut insulicient to precipitato any ot' the sodium ohlorid und then subjecting the impurities to a plurality of reagents respectively reactive upon the sui-eral 'impurities to render them separable from the sodium clilorid and adapted to add to thc solution un clement of sodium chlorid.

The process ot separating from sodium chlorid a plurality of impurities and recovering said impurities, which consists in adding to a solution of the impure sodium chlorid, a plurality ot reagents respectively adapted to render the several impurities separable from the sodium chlorid; said reagents being added successively in the order in which they are desired to act upon the several impurities to be removed and in the order in which the impurities are to be recovered; and said reagents containing and being adapted to add to the solution sodium chlorid which combine with elements aL readyy present forming more and only sodium chlorid in addition to that already in solution and leaving only sodium chlorid in solution.

7. The. process of removing from salt a plurality of impurities each containing an element of salt, which consists in treating the impure salt with a plurality of reagents each of which is reactive as to one of the impurities and contains an element which combines with the salt lproducing element; of the impurity and adds to the sodium chlorid solution, more sodium chlorid.

S. The process of purifying salt which consists in treating the impure saltwith a reagent that converts the impurity into one containing an cle-nient of salt and the-n subjecting said impnrit)Y to another reagent containing an clement which combines with the salt producing element of the impurity to produce salt in addition to that already in solution.

t). The process of purifying salt which consists in adding to a solution of the impure salt, a reagent that is reactive as to the impurity to be removed and also con tains a residual element which is one of the elements of salt and thereafter adding to the resultant solution another reagent containing un element that combines with the said residual element' to form salt in addition to that already in solution.

10. The process of purifying salt containing a plurality of impurities which consists in addinglr to the solution of impure salt, a series of reagents, cach ot which precipitates one of the impurities to be removed` or a constituent thereot and at the. same time leaves in solution an ingredientl or ingredients which increase or assist. in in creasing the mass of salt.

l1. The process of purifyin r salt containing impurities, including sul ates of alkali and earth metals which consists in ucidulab ing the solution, adding barium chlorid to the aciduluted solution 1n quantity suliclent to recipitate the sulfuric radical, theuueutra izin the acidulatcd solution and snnultaneons y precipitating therefrom the contained impurities exec ting those having an element of salt in tieir composition and thereafter adding a reagent composed o elements, one of which combines with the salt producing elements of the impurities 'to produce salt 1n addition to that already'ln solution while the remainder combnie'with the remaining elements of the impurities to form a precipitate. i

l2. The rocess of separating from so dium chlori impurities in the form of oxlds of iron and other heavier metals, sulfatos of alkali and earth metals and chloride of earth metals, which consists in adding to the acidulated saturated solution of the salt containing said impurities, barium chlorid,

sodium carbonate and sodium hydroxid in the order named in quantities sufficient to precipitate the impurities in the form of barium sulfate, ferrie hydroxid, carbonate of calcium and magnesium hydroxid and combining the sodium and chlorin elements of the reagents and of the impurities to form sodium chlorid in addition to the so diuxn chlorid sought to be purified.

13. The process of purifying sodium chlorid containing as impurities sulfatos, which consists in adding to a solution of the impure sodium chlorid, barium chlorid in suihcient quantity to convert the sula-tes into chloride, .thereby increasing in the solution the content of a salt producing element, and at the same time precipitating barium sulfate.

14. The process of separating sodium sulfate and other sulfates from sodium chlo rid which consists in adding barium chlorid and producing barium sulfate, sodium chlorid in addition to that already contained and other chlorids and thereafter adding sodium carbonate and thereby converting the chloride into more sodium chlorid and precipitating their bases as carbonates.

15. The process of separating from sodium chiorid ferrie-chlorid, sodium sulfate, cal cium sulfate, magnesium sulfate, calcium chlorid, and magnesium chlorid, which consists in adding to a solution of sodium chlorid containing said impurities, barium chlorid suiiicient to precipitate the sulfuric radieals as barium sulfate and at the same time convert their bases into chloride thereby adding to the solution more sodium chlorid and more of other chloride named; then add- 1n to the solution, an alkaline substance (a kalrne or alkaline carbonate) suilicient to prec1p1tate ferrie hydroxid and leave calciunl chlorid and ma nesium chlorid in solutlon and then adding sodium carbonate snlicient to precipitate the calcium as culcnnl carbonate und convert its chlorin into still lnorc sodium chlorid.

lll. 'lhc process of separating from sodinni chlorid, ferrie-chlorid, sodium sulfate, calcium sulfate, magnesium sulfato, calcium chlorid, and magnesium chlorid, which consists in adding to a solution of sodium chlorid containing said impurities, barium chlorid sufficient to precipitate the sulfuric radicals as barium sulfate and at the same time convert their bases into chloride thereby adding to the solution more sodium chlorid and more of other chloride named; then adding to the solution, an alkaline substance (alkaline or alkaline carbonate) suilicient to precipitate ferrie hydroxid and leave calcium chlorid and magnesium chlorid in solution; then adding sodium carbonate sniiicient to precipitate the calcium as calcium carbonate and convert its chlorin into still more sodium chlorid and then adding more sodium carbonate sufficient to con vert the magnesium of the magnesium chlorid into magnesium carbonate and its chlorin into still more sodilun chlorid.

17. The process of separating from sodium chlorid ferrie-chlorid, sodium sulfate, calcium sulfate, magnesium sulfate, calcium chlorid, and magnesium chlorid, which consists in adding to a solution of sodium chlorid containing said impurities, barium chlorid sufficient to precipitate the sulfuric radicals as barium sulfate and at the saine time convert their bases into chlorids thereby adding to the solution more sodium chlorid and more of other chlorids named; then adding to the solution, an alkaline substance (alkaline or alkaline carbonate) suliicicnt to precipitate ferrie hydroxid and leave calcium chlorid and magnesium chlorid in solution; then adding sodium carbonate suicient to precipitate thc calcium as calcium carbonate and convert its chlorid into still more sodium chlorid; and then adding sodium hydroxid to convert the magnesium of the magnesium chlorid into magnesium hydroxid and its chlorin into still more sodium chlorid.

18. The process of separating lrom scdilnn chlorid, impurities in the form of oxide and hydroxide of heavier metals and sulfates of alkali and earth metals and chloride of earth metals which consists in adding to a solution of the impure salt, bariun.- chlorid, followed by sodium carbonate und Sodium liydroxid and thereby precipitating! the impurities in the form of ferrie h vdroxid, barium sulfate, and carbonatos or hydroxide of the earth metals, and combining the sodium and chlorin elementsof the im uritics and reagents to form salt in addition to that sought to be inuied.

19. The process of separating from a lution of sodium chlorid impurities in the touufof. oxide otA iron, alumina, etc., which consists. in adding to the iun'nn'e solution just suilicient hydrochloric acid lo convert the basic impuritiesI into chlorids.

2.0. The process of separating from a solution of sodium chlorid impurities in the 'l forni of oxtds of iron alumina, etc., which consists in adding to the impure solution hydrochloric acid to convert their bases into chloride, then adding sodium ferro cya-nid to precipitate the iron content as Prassian blue and produce sodium chlorid, in addition to that in the solution to be purified.

2l. The process of separating from a solution of sodium chlorid impurities in the form of oxide of iron, alumina, etc., which consists in adding to the impure solution hydrochloric acid to convert their bases into chloride, then adding sodium ferro cya-nid to precipitate the iron content as Prussian blue and at the saine time combining the sodium element of the reagent with the chlorin elements of the impurities to form salt.

2:2. The process of separating from a solution of sodium chiot-id, impurities in the form of oxids of iron, a1u1nna, etc., sulfates of alkali and earth metals, which consists in adding to the impure solution, hydro chlorc acid` to convert the oxids into chlo rids then adding ferro cyanid of sodium to precipitate the iron content as Prussian blue and combine its chlo'in element with the sodium element of the rea-gent to forni sodium chlorid, then adding barium chlorid to precipitate the sulfuric radicals as barium sulfate and convert their bases into chloride.

23. The process of separating from a solution of sodium chlorid, impurities in the form of oxids of iron, alumina, etc., sulfates of alkali and earth metals, which consists in adding to impure solution, hydrochloric acid, to convert the oxids into chlorids then adding ferro cyanid of sodium to precipitate the, iron content as Prussian blue and combine its chlorin clement with the sodium element of the reagent to torni sodium chlorid, then adding barium chlorid to precipitate the sulfuric radicals as barium sulfate. and convert their bases into chlorids, then adding to the solution just sufficient of an alkali to neutralize any tree acid.

24. The process of separating from a solution of sodium chlorid, impurities in the form of oxids of iron alumina, etc., sulfatos of alkali and earth metals, which consists in adding to the impure solution, hydrochloric acid, to convert the oxids into chloride then addin r ferro cyanid of sodium to precipitate tlie iron content as Prussian blue and combine its chlorin element with the sodi uni element of the reagent to form sodium chlorid, then adding barium chlorid to precipitate the sulfuric radicals as barium sulfates and convert their bases into chloride,

then adding to the solution just sufficient of an alkali carlmualc to neutralize any :tree arid, percipilale a small per ccnl. oli calcium as calcium carbonate and carry down any remaining heavier metals as carbonatos and at the saine time con'ibine the .sodium elcinent ot' the reagent with the chlorin element-s ot' the impurities to form sodium clilorid.

zo. l'hc process of separating from so diuin chiot-id impurities inthe torni of oxids of iron, alumina., ctc., sulfatos of alkali and earth metals, and chlorids of calcium and magnesium which consists in adding to the impure solution, hydrochloric acid, to convert. the oxids into chlorids, then adding sodium ferro cyanid to precipitate the iron content as Prussian blue and combine its ehlorin element with the sodium element of the reagent to form sodium chlorid, then adding barium chlorid to precipitate the sul furie radicals as barium sulfatos and convert their bases into chloride, then adding to the solution just sulicient of an alkali carbonate to neutralize any free acid, pr cipitate a small per cent. of the calcium chlorid present as calcium carbonate and carry down any remaining heavier metals as carbonatos and at the same time combine the chlorin elements of the impurities with the sodium element of the reagent to form sodium chlorid, then adding sodium carbonate to precipitate calcium chlorid as calcium carbonate and combine its element with the sodium element of the reagent to form sodium chlorid` 2G. The process of separating from s0- dium ohlorid impurities in the form of oxids of iron, alumina, etc., sulfatos of alkali and earth metals, and chloride of calcium and magnesium which consists in adding to the impure solution, hydrochloric acid, to convert the oxiils into chlorids, then adding sodium ferro cyanid to precipitate the iron content as Prussian blue and combine its chlorin element with the sodium element of the reagent to form sodium chlorid, then adding barium chlorid to precipitate the sulfuric radica-ls as barium sulfates and c011- vert their bases into chlorids, then adding to the solution just. sufiicient of an alkali carbonate to neutralize any free acid, precipitate a. small per cent. of the calcium cl'ilorid present as calcium carbonate and carry down any remaining heavier metals as carbonatos and at the same time combine the chlorin elements ot' thi` impurities with the sodium element of the reagent to form sodium ehlorid. then adding sodium 'arhtmatc tu |:n'ecipitate calcium chiot-id as calcium carbonate and combine its element with the sodium element ot' the reagent to form sodium chlorid and then adding: sodium can bollate to precipitate magnesium as mag. nesinm carbonate and combine its element with tho sodium olenuenl of llw rungen! lo form smliinn i-hloi'iil.

27. The noccss of sepui'uting from s0 linnn chloi'lil impurities in the form of oxids 5 of iron, illumina, etc., sulfatos of zillcali and earth inelnls, und ohloiids of enloium und magnesium which consists in adding to the impure solution, hydrochloric acid, tio con vert the oxids into chlorids, then uddnig sodium ferro cyanid to precipitate the iron content :is Prussian blue and combine its chlorin element with the sodium element of 2n present as calcium carbonate and carry down uny renniining heiwiui' metals :is cui'bonutes und nt the sume time combine the clilorin eleineuls of the impurities; with the sodium element of the reagent to `form sodium `elihnid, then adding sodium carbonate to precipitate calcium chlorid as calcium carbonate und combine its element with the sodium element of the reagent to form sodium clllorid and then adding sodium hydroxid to precipitate magnesium as magnesium hydioxid and combine its chloiin element with tlie sodium element of the reagent to form sa t.

The foregoing specification signed at Bultimore this fifteenth day of May, 1909.

CHARLES GLASER. GEORGE J. MULLER. In presence of two witnesses: WVM. H, H. RALEIGH,

lrus'ixw Bi'inxscHEU-En. 

